1. Field of the Invention
The present invention relates to an audio signal processing apparatus for recording a plurality of kinds or a plurality of systems of audio signals on a recording medium and/or for reproducing a plurality of kinds or a plurality of systems of audio signals recorded on the recording medium.
2. Description of Related Art
At present, there are various audio signal processing apparatuses for recording a plurality of kinds or a plurality of systems of audio signals on a recording medium and/or for reproducing a plurality of kinds or a plurality of systems of audio signals recorded on the recording medium. For example, in the case of a digital video tape recorder (VTR) of the camera-integrated type, a recording format according to which a plurality of kinds of audio signals (namely, two systems of stereophonic audio signals, i.e., a total of four channels of audio signals) can be recorded on magnetic tape together with video signals corresponding to the audio signals, is available.
Further, considering an apparatus capable of recording a plurality of kinds of audio signals in accordance with the aforementioned recording format, for the purpose of making it possible to record the aforesaid plurality of kinds of audio signals in a good S/N condition by effectively utilizing a dynamic range of a magnetic tape serving as a recording medium, it is conceivable that the apparatus is provided with a volume for setting a recording level in each channel in such a manner as to optimally adjust the levels of a plurality of kinds of audio signals (hereinafter, two systems of stereophonic audio signals will be referred to as “stereophonic-1” signal and “stereophonic-2” signal) when both systems of audio signals are recorded together on the magnetic tape. Then, the levels of the plurality of kinds of audio signals are adjusted by operating the volume, and the level-adjusted audio signals are recorded on the magnetic tape. Moreover, when both of the “stereophonic-1” signal and the “stereophonic-2” signal are reproduced together from the magnetic tape, it is conceivable that the apparatus has a mode in which the aforementioned “stereophonic-1” signal and the aforesaid “stereophonic-2” signal are reproduced independently of each other, and another mode in which the “stereophonic-1” signal and the “stereophonic-2” signal are reproduced while being mixed at an arbitrary mixing ratio which is freely settable.
However, in the aforementioned apparatus which is provided with the volume for setting a recording level so as to optimally adjusting the levels of the “stereophonic-1” and “stereophonic-2” signals for recording and is capable of recording the “stereophonic-1” and “stereophonic-2” signals while setting the recording levels thereof by using the volume during recording, and of reproducing the “stereophonic-1” and “stereophonic-2” signals in accordance with the mode of mixing the “stereophonic-1” and “stereophonic-2” signals at an arbitrary mixing ratio which is freely settable during reproduction, there arises the following problem. Depending upon a certain manner of setting the recording levels of the audio signals by the recording-level setting volume, the dynamic range of magnetic tape serving as a recording medium cannot be effectively utilized to record the audio signals. Moreover, during reproduction, if the “stereophonic-1” and “stereophonic-2” signals are mixed at a desired mixing ratio so as to be reproduced, the state of reproduction results in poor S/N.